The present invention relates generally to television with signal formatting for providing more than one information signal in the same channel during sync or blanking intervals; and more particularly to a system for monitoring a digital data bus, selecting data, and encoding it for multiplexing with a video signal. The particular system provides digital capability for cockpit television instrumentation systems using a video recorder.
There are now a number of systems for dissemination of data in digital form along with a television signal, e.g., during the vertical blanking interval, so that information other than the video signal can be included in the same channel.
For example, U.S. Pat. No. 4,218,697 to Leventer discloses a digital logic circuit for digital encoding and decoding of information, which encoding is performed on a standard TV video signal. U.S. Pat. No. 4,335,402 to Holmes discloses a teletext system which transmits auxilliary information before the vertical sync pulse in the vertical blanking interval to avoid interference to the normal transmitted picture. U.S. Pat. No. 4,380,027 to Leventer et al discloses a video data encoding system for encoding digital data to be transmitted by way of scan lines of a television video signal. U.S. Pat. No. 4,308,588 to Hernandez et al discloses a circuit for arranging video data in a block format.
Video instrumentation systems are being used in an increasing number of airborne applications such as replacement of the traditional film gun camera. There is a wide range of digital instrumentation requirements for flight testing, dry-run gunnery scoring, combat/mission documentation, operational training, and the inflight collection of maintenance data.
In any airborne instrumentation application requiring the recording of both image data and digital data, the ability to use one recorder for both data types could provide several advantages. The advantages include reduced instrumentation volume and the synchronization of digital and image data. The electronics necessary to multiplex the digital and image data for instrumentation could easily achieve volume/cost/reliability advantages over the alternate approach of separate digital and video instrumentation systems.